list-attachments

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description carries the full burden. It clearly states the return values (names, MIME types, sizes, count) and implies read-only behavior. However, it does not mention potential edge cases or limitations, but for a simple list operation, this is adequate.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences plus a return summary, highly front-loaded with the 'Use when' instruction. Every sentence adds value with no redundancy or filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool has an output schema (as indicated by context signals), the description only needs to summarize the output, which it does. It also provides sufficient context for the single parameter and usage flow, making it complete for a simple list operation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The only parameter 'id' is described as the message ID, and the description adds context by telling the user to get the ID from search-messages or list-messages first. Schema coverage is 0%, so the description compensates well by explaining the parameter's purpose and source.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description explicitly states the verb 'enumerating' and the resource 'attachments of a message by id', and clearly distinguishes from sibling tools fetch-attachment and save-attachment by specifying what it returns (names, MIME types, sizes) and when to use it.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description includes both 'Use when' and 'Do not use when' sections, with specific alternatives (fetch-attachment, save-attachment) and a prerequisite step (get message id from search-messages or list-messages first).

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.